Humans who interact with computers and robots often attribute emotions to their machine cohorts. That's why we curse at our inefficient laptops, or say thank you to the robot who smiles and hands us drinks. Now a group of researchers in Germany have proven that the human brain has a hard time distinguishing between humans and humanoid robots. This neural hardwiring could mean that we'll never be able to treat humanoid robots as if they are emotionless machines. Even if they are.

Using fMRI imaging technology, the researchers scanned the brains of people playing games with four different opponents: a computer notebook, a Lego robot, a humanoid robot (pictured), and a human. All game partners made exactly the same moves, so there was no difference in the game itself.


The results were fascinating. According to a release from PLoS One, where the study was published this morning:

The results clearly demonstrated that neural activity in the medial prefrontal cortex as well as in the right temporo-parietal junction linearly increased with the degree of "human-likeness" of interaction partners, i.e. the more the respective game partners exhibited human-like features, the more the participants engaged cortical regions associated with mental state attribution/mentalizing.

Further, in a debriefing questionnaire, participants stated having increasingly enjoyed the interactions most when their respective interaction partners displayed the most human features and accordingly evaluated their opponents as being more intelligent.

This study is the first ever to investigate the neuronal basics of direct human-robot interaction on a higher cognitive level such as mentalizing. Thus, the researchers expect the results of the study to impact long-lasting psychological and philosophical debates regarding human-machine interactions and especially the question of what causes humans to be perceived as human.

What I find interesting about this is the idea that there is a kind of sliding scale of humanness in our brains. Completely non-humanoid, brain-in-a-box computers evoke the least emotional response, and the humanoid evoke the most. Not mentioned in this study, however, is what makes our brains click over into "this is a humanoid" mode. For example, many people who watched the movie Wall-E, whose robots are barely humanoid, had strong emotional reactions to the robotic creatures. Similarly, people respond to a totally non-humanoid creature like HAL from 2001 as if it has human feelings too. So clearly we go by more than physical cues when our brains evaluate whether something counts as humanoid or not.

Can Machines Think? Interaction and Perspective-Taking with Robots via fMRI [PLoS One]